THE INFLUENCE OF GENOTYPIC FACTORS ON LONGEVITY AND LIFETIME PRODUCTION OF DAIRY COWS

Abstract

The influence of genotypic factors (breed, Holstein share heredity, line or related group, sire) on the longevity and lifetime production of dairy cows has been investigated. The study was carried out in a retrospective statistical experiment on the commercial dairy farm “Terezyne”, which located in Kyiv region. The formed matrix of observations in the sta format generally contained information about 5703 cows for 458 variables. Holstein cows were characterized by higher longevity (1489 ± 27.8 days) and higher lifetime milk production (21940 ± 500.9 kg), the lowest longevity and lifetime milk production had cows of Ukrainian Red-and-White dairy breed. Holstein cows compared to animals of Ukrainian Red-and-White dairy breed had in average more lactations (+0.57 ± 0.187) and higher number of total calves (+0.59 ± 0.244). They had an advantage in lifespan by 218 ± 80.1 days, productive lifespan – by 326 ± 82.0 days, total lactation length – by 282 ± 62.2 days. During the lifetime, they produced 4119 ± 1398.4 kg more milk and 549.3 ± 99.62 kg more milk fat and milk protein. Lifetime daily milk yield of Holstein cows was on average 2.6 ± 0.37 kg higher, lifetime daily milk fat and milk protein – 208 ± 26.7 g more compared to animals of the Ukrainian Red-and-White dairy breed. Cows of Ukrainian Black-and-White dairy breed in most traits were intermediate between Holstein and Ukrainian Red-and-White dairy breed. While increasing Holstein share heredity the longevity and lifetime production of cows tended for curvilinear growing. Lifetime of Holstein cows (100%) in the herd was 0.16 ± 0.405 lactations and 325 ± 170.7 days (P < 0.1) longer compared to animals with Holstein share heredity less than 75%. Their lifetime milk production was 8969 ± 2351.6 kg (P < 0.001) higher, lifetime milk fat and milk protein production by 709.9 ± 164.73 kg (P < 0.001) higher, lifetime daily yield by 3.0 ± 0.62 kg (P < 0.001) and 250 ± 43.5 g (P < 0.001), respectively, higher. The cows of Starbuck 352790, Valiant 1650414 and Elevation 1491007 lines and daughter of V. Astronomer 2160438 and H. R. Artist 6284191 sires showed the best longevity and lifetime production. The advantage of cows of the related group of Starbuck 352790 in comparison to animals of other lines in total number of lactations was 0.28–1.29, number of total calves – 0.16–1.20, lifespan – 90–508 days, productive lifespan – 116–603 days, total lactation length – 98–500 days, lifetime milk production – 1402–12161 kg, lifetime milk fat and milk protein production – 115–892 kg. Daughters of bull V. Astronomer 2160438 characterized by 0.96–2.72 more total number of lactations than daughters of other bulls; they had 0.80–2.33 higher average number of total calves. In terms of lifespan, productive lifespan and total lactation length, daughters of this bull were predominated the daughters of other bulls by 392–1037, 297–1143 and 278–971 days, respectively. One-way analysis of variance showed that the greatest influence on longevity and lifetime production of dairy cows had a paternal inheritance, the lowest – breed, it means there is a tendency of increasing the influence of genotypic factors on the researched traits while reducing the level of selection group in the system hierarchy. The strength of breed influence (higher level of intraspecific selection system hierarchy) on the traits of longevity and lifetime production of cows ranged from 1.1 to 12.5%, Holstein share heredity – 3.9 to 19.5%, line or related group – 4.0–19.8% and paternal inheritance – 25.0–47.6%. Greater degree of influence of paternal inheritance is explained both by the lowest (basic) level of intrabreed system hierarchy (the closest level of intragroup kinship) and (partially) by a much higher number of gradations of the organized factor.